The invention relates generally to controls for a gyratory or cone crusher.
Gyratory crushers or cone crushers are characterized by crushing heads having a generally cone-shaped outer surface, which are mounted to undergo gyratory motion. The cone-shaped crushing head of a gyratory crusher is generally centered about a cone axis that is angularly offset from a vertical crusher axis generally centered through the crusher. The outer surface of the head is protected by a replaceable mantel.
The crushers are further characterized by a bowl-shaped member, sometimes referred to as a concave or bonnet, disposed in an inverted position generally over the cone-shaped crushing head and centered on the vertical crusher axis. The inner surface of the bowl-shaped member is protected by a replaceable bowl liner. The outer dimensions of the head and mantel are smaller than the corresponding inner dimensions of the bowl liner. The head is mounted such that there is a space between the mantel and the bowl liner, sometimes referred to as the "crushing chamber" or "crushing cavity". The volume of the crushing cavity can be increased by altering the shape of the exposed surface of the bowl liner and/or the shape of the exposed surface of the mantel. It can also be increased or decreased by vertically adjusting the separation between the mantel and the bowl liner. The bowl-shaped member has an upper opening through which material to be crushed can be fed into the crushing cavity.
The smallest distance between the mantel and the bowl liner at the bottom of the crushing cavity is called the "closed side setting" or "setting" of the crusher. The width of the setting determines the size of crushed materials operably produced by the crusher. The setting can be enlarged to increase the size of the crushed material produced by the crusher, and can be decreased to reduce the size of the crushed material produced by the crusher. The setting can be adjusted by simply raising or lowering the elevation of the bowl liner relative to the elevation of the cone head. The setting of some cone crushers is adjusted by raising or lowering the head. The difference between the width of the closed side setting and the spacing between the mantel and the bowl liner at the bottom of the crushing cavity directly opposite from the closed side setting, sometimes called the "open" side or "open side setting", is called the "throw" or "stroke" of the crusher.
The small angular offset of the cone axis relative to the vertical crusher axis is provided by mounting the head on an eccentric element, or other suitable mounting. The head is caused to gyrate relative to the bowl-shaped member by rotating that mounting or eccentric element. As the eccentric element rotates, one side of the head is caused to approach the bowl liner until it attains the closed side setting while the opposite side of the head recedes from the bowl liner until it simultaneously attains the open side setting. The closed side setting and open side setting operably travel around the periphery of the lower end of the crushing cavity as the eccentric element is rotated, each making a complete revolution around the cone head for each revolution of the eccentric element. The magnitude of the gyration is determined by the angle that the cone axis is offset from the crusher axis and by the location of the point at which those two axes most closely approach or intersect.
State-of-the-art gyratory or cone crushers are generally driven by a horizontally disposed countershaft which radially extends into a lower part of a generally cylindrical crusher housing. An inner end of the countershaft is coupled through a pinion and ring gear to the eccentric element to rotatably drive the eccentric element.
A motor (either electric or combustion) is used to drive the crusher. The speed of the motor, the size ratio of the pulleys on the motor and the crusher, and the gearing of the eccentric element determine the speed at which the head gyrates, sometimes referred to as the "gyrational speed". The gyrational speed selected for each crusher depends on the particular application for which the crusher is to be used. Increasing or decreasing the gyrational speed is usually a matter of changing the speed of the motor, changing the relative sizes of the pulleys on the motor and the crusher, and/or changing the gear ratios for the eccentric.
The gyratory or gyrating motion of the cone-shaped crushing head performs a material comminution action on material, such as rock, ore, coal and other hard substances, as the material is fed through the bowl opening into the crushing cavity. The material typically moves by gravity through the annular space between the exposed surface of the stationary bowl liner and the exposed surface of the cone-shaped mantel. As the gyrating head approaches the liner, it crushes the material; as it recedes from the liner, the material falls farther down the crushing cavity to undergo further crushings during subsequent revolutions of the eccentric member and as the separation between the bowl liner and the head gradually decreases from top to bottom. This progressive crushing action repeatedly occurs until the crushed material is discharged from the bottom of the crushing cavity.
A problem with prior art crushers is the inability to automatically detect and eliminate a bowl float condition. Of course, some of such bowl float conditions are quickly alleviated by tramp iron relief systems. If prolonged, however, a bowl float condition can quickly cause substantial damage to a crusher.
Another problem with prior art crushers is the inability to operatively and automatically compensate for wearing away of the crushing surfaces of a bowl liner and a mantel forming a crushing cavity within the crushers.
A further problem with prior art crushers is the inability to expeditiously arrange for bowl liners thereof to be vertically hoistable for maintenance or replacement.
What is needed is a crusher having an automatic control system or an automatic control system for a crusher wherein a bowl float condition is automatically detected and eliminated, for automatically compensating for wearing away of the crushing surfaces of the crusher as the crusher is being operated, and for automatically adjusting a bowl liner such that the bowl liner is vertically hoistable from the crusher.